WASHINGTON (AP) — The chairman of the House Intelligence Committee says it appears the much-criticized national electronic surveillance program foiled “dozens” of terrorist plots.

Michigan Republican Rep. Mike Rogers, who is presideing over an open hearing of the intelligence panel today, says he expects the head of the National Security Agency, Army Gen. Keith Alexander, to declassify additional information about the program. The Obama administration already has declassified data crediting the NSA program with breaking up a planned attack on New York City’s subway system.

Rogers tells NBC’s “Today” show that lawmakers “know there are dozens” of terrorist plots thwarted by the NSA program. And he says Congress also wants to learn much more about how NSA contract employee Edward Snowden, who publicly revealed information about the program, got access to such highly sensitive data.